This invention relates generally to data transmission and more specifically to high speed data distribution over residential electrical wiring.
High speed transmission of data throughout a residence facilitates performing home automation functions such as home security and appliance controls. Residential electrical systems can be used for data communication within a residence. For existing residences, wiring in the residential electrical systems is advantageous to use because, in most instances, use of such wiring facilitates installation of a communication system.
The installation of dedicated data wiring is one alternative to the use of the residential electrical system, for data communication, but is undesirable due to cost and other factors. The other factors include the invasiveness of dedicated data wire installation in existing structures either requiring unsightly installations along baseboards, ceilings, and walls or damage and repair to walls when attempting to install behind existing wallboard or plaster walls.
Data can be transmitted over residential electrical wiring using a neutral-to-ground circuit of the residential wiring system. Using neutral-to-ground circuits for the transmission of data within a residence has advantages over line-to-ground or line-to-neutral circuits since the voltage present on the line circuit is avoided. However, neutral-to-ground data transmission is also complicated, as is line-to-ground or line-to-neutral data transmission in that the impedance of the circuit changes as devices are plugged into the circuit. Therefore impedances encountered by a data transceiver is constantly changing. The changing impedance affects the nature of optimal signaling techniques and also affects the bandwidth or data carrying capacity of the data transceivers.
It would be desirable to be able to periodically diagnose the impedance of the neutral-to-ground circuit and compensate for detected impedance changes thereby enabling the circuit to maintain a wide data bandwidth thus providing a reliable high-speed data transmission medium which is available to most existing homes and eliminates the cost involved with installation of dedicated data wiring.